A player in combat with multiple rock crabs.
Rock Crabs are aggressive monsters that look like harmless rocks while disguised, but attack when walked by. Unlike most other enemies and NPCs, Rock Crabs are not marked with yellow dots on the player's minimap; this is probably due to the crabs' appearance, which camouflages them as rocks.
Players can tell if a rock is a Rock Crab by looking at the rock's shape; Rock Crabs are tall oval shaped while normal rocks in their area are mostly in large clusters of shattered pieces. Another way to tell is by right clicking on them. If the text colour is yellow, it is a Rock Crab. If the text is blue, it is just a prop.
Rock Crabs become docile if the player has not left the surrounding area in a certain amount of time (roughly between ten and twenty-five minutes). To make the crabs aggressive again, exit the surrounding area (halfway to the entrance to the village in Rellekka, or by entering and exiting the entrance to Keldagrim) and enter again. You can also find one Rock Crab that will be aggressive, kill it then you can continue killing other crabs. As they are "dormant" until "awoken" by a passing player, rock crabs cannot be attacked until they are made aggressive once more.
Rock Crabs are excellent for training at all combat levels due to their low Defence and high Hitpoints, though low level players should consider bringing food. Rock Crabs used to be a popular melee training monster until the release of Sand Crabs, and the subsequent release of Ammonite Crabs, which are now more preferred options for training.
However, due to Sand Crabs being very crowded, some players choose to train on Waterbirth Island, as it has multiple convenient spawn locations where a player can stand still and always have 3-4 Rock Crabs attacking them at any moment, making it comparable to the experience rates of Sand Crabs. The player can simply reset the aggressiveness of the Rock Crab by running back to the boat to leave Waterbirth Island, then running back to their desired training spot.
The spot to avoid cannonading in Rellekka.
Note: Dwarf multicannons may be used here, unlike with the other types of crabs commonly used for training. This can make training for other players difficult. There is, however, a way to avoid the cannon's fire. If a player moves to the west-most part of the multi-combat zone, most cannon fire can be avoided. There are three rock crab spawns near this location, which makes it a decent spot. Although the cannon's fire can be avoided, it is best to switch to another world when faced with overcrowding.
The following drop rates are provided by Jagex, unless otherwise specified.
The average Rock Crab kill is worth 101.5.
There is a 1/128 chance of rolling the gem drop table.
|Nothing||N/A||1/256.47; Never[d 1]||N/A||N/A|
|Uncut sapphire||1||1/512; 1/260[d 2]||434||15|
|Uncut emerald||1||1/1,024; 1/520[d 2]||674||30|
|Uncut ruby||1||1/2,048; 1/1,040[d 2]||1,229||60|
|Nature talisman||1||1/5,461.33; 1/2,773.33[d 2]||775||2|
|Uncut diamond||1||1/8,192; 1/4,160[d 2]||2,630||120|
|Loop half of key||1||1/16,384; 1/8,320[d 2]||10,448||60|
|Tooth half of key||1||1/16,384; 1/8,320[d 2]||10,934||60|
|Rune javelin||5||1/16,384; 1/8,320[d 2]||840||1,200|
|Rune spear||1||1/262,144; 1/15,600[d 2][d 3]||11,987||12,480|
|Shield left half||1||1/524,288; 1/31,200[d 2][d 3]||65,576||66,000|
|Dragon spear||1||1/699,050.67; 1/41,600[d 2][d 3]||36,869||37,440|
- ↑ 1.0 1.1 Elite clue scrolls or elite caskets are only dropped when completing a elite cryptic clue asking the player to kill a Rock Crab.